Orwell[18]

You may recall this being discussed on the nmos thread. I've added two
more circles of tetrads which may be of interest.

Orwell[18]

[7, -3, 8, -21, -7, 27]
[1, 36/35, 15/14, 35/32, 8/7, 7/6, 5/4, 9/7, 4/3, 48/35, 35/24, 3/2,
14/9, 8/5, 12/7, 7/4, 49/27, 15/8]
[8/7, 4/3, 14/9, 49/27, 15/14, 5/4, 35/24, 12/7, 1, 7/6, 48/35, 8/5,
15/8, 35/32, 9/7, 3/2, 7/4, 36/35]

Circles of tetrads, generator 7/6

[1, 21/16, 3/2, 7/4] [1, 6/5, 3/2, 9/5] [1, 9/7, 3/2, 9/5] [1, 7/6,
3/2, 7/4]
[1, 21/16, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 21/16, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 6/5, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 8/7, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 7/4] [1, 8/7, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 7/4]
[1, 5/4, 3/2, 5/3] [1, 8/7, 3/2, 12/7] [1, 9/7, 3/2, 12/7] [1, 7/6,
3/2, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 9/7, 10/7, 12/7] [1, 7/6,
10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
7/6, 10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
7/6, 10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
7/6, 10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
7/6, 10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
7/6, 10/7, 5/3]
[1, 5/4, 10/7, 5/3] [1, 8/7, 10/7, 12/7] [1, 60/49, 10/7, 12/7] [1,
10/9, 10/7, 5/3]